Navicula digitoradiata var. striolata Grunow

Wojtal, Agata Z., Ognjanova-Rumenova, Nadja, Buczkó, Krisztina, Siwek, Janusz & Vijver, Bart Van De, 2015, Revision of Navicula striolata (Grunow) Lange-Bertalot and N. rumaniensis Hustedt with the description of N. friedelhinziae sp. nov., Phytotaxa 204 (3), pp. 177-192 : 179-180

Navicula digitoradiata var. striolata Grunow in Cleve & Grunow ( Figs. 1–7 )

Original description:— “Sehr ähnlich der hier abgebildeten schmalen Form von N. digito-radiata , aber mit deutlicher quergestichelten Querstreifen. Länge 0,06–0,07 mm., Schaalenbreite 0,013 mm. Querstreifen 8–9 in 0,01mm ” ( Grunow 1880).

Type:— SWEDEN. “ Degeberga , Schonen leg. Cleve. (Cl. u. Möll. Diat. Nr 25 zwischen N. reinhardi )”, GENT! Van Heurck Collection slide II-2-C1. Lectotype (designated here, illustrated in Fig. 1 ): slide by Cleve & Möller no. 25 housed in Van Heurck Collection in the Botanic Garden Meise, leg. Cleve.

LM:— ( Figs. 1–7 ): Valves narrowly lanceolate with clearly convex margins and broadly rounded, non-protracted apices. Valve dimensions (n=25): length 46–64 μm, width 10.5–11.5 μm ( Figs. 1–7 ). Axial area linear to linear-lanceolate, rather narrow, gradually widening towards the central area. Central area variable, usually relatively small, apically elongated, bordered by alternating longer and shorter striae. Raphe branches distinctly lateral. Proximal raphe ends unilaterally deflected towards the secondary side of the valve, indicated by a clear Voigt discordance. Distal raphe endings apparently hooked to the opposite side as the proximal endings. Striae distinctly radiate and more widely spaced in the mid-valve becoming parallel or slightly convergent and more densely arranged towards apices, 8–9 in 10 μm. Lineolae clearly discernible in LM, 24–28 in 10 μm.

Figures

FIGURES 1–14. LM. 1–7. Navicula digitoradiata var. striolata Grunow in Cleve & Grunow. 1. The lectotype of N. digitoradiata var. striolata Grunow in Cleve & Grunow exsiccata n° 25 (collection entry II-2-C1) sampled from Degeberga (Sweden), housed in Van Heurck Collection. 8–14. Navicula reinhardtii var. gracilior Grunow, Types du Synopsis de Belgique nº 80 (collection entry V-25-B8), from from Rouge-Cloître (Belgium), in Van Heurck collection. 13. The lectotype of N. reinhardtii var. gracilior Grunow, slide II-2-C1, housed in Van Heurck Collection. Scale bar = 10 μm.